Controlling electric arcs.



No. 7|5,9o|. P-ate n'te'd nee; I6, I902.

amomsou. 1

CONTROLLING ELEQTBIDARGS.

(Application filed Apr. 12,1902.)

WiCne sses; Inventor .5 44 ElihuThomsqn yw .4: THE Nomus PETERS co.vacuum-no. wasmmmmo U ITE ST TEs PATENT OFFICE.

ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEWV YORK.

CONTROLLING ELECTRIC ARCS.

SPECIFICATION formingpart of Letters Patent No. 715,901, dated. December16, 1902.

Application filed ran 12, 1902.

Serial No. 102,516. (No model.)

To alt whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States,residing at Swampscott, in the county of Essex, State of Massachusetts,have invented certain new and useful Improvements in ControllingElectric Arcs, (Case No. 2,599,) of which thefollow ing is aspecification.

My present invention relates to the control of electric arcs and tomechanism for effecting this purpose.

The novel features of the invention willbe pointed out in the appendedclaims, while in the following specification will be given a detaileddescription of certain embodiments of myinvention, together with anexplanation of the mode of operation thereof.

In the drawings, in connection with which the following specification isto be read, Figures 1, 2, and 3 represent an arrangement for controllingan electric are produced by single-phase alternating current, whileFigs. 4, 5, and 6 set forth an arrangement for controlling an arcproduced by multiphase alternating current.

In Fig. l the pencils 1 and 2 represent two stationary electrodes,between the lower ends of which an arc is to be formed. To start the arebetween these electrodes, I make use of a starting-electrode 3, whichwhen no current is flowing is held by a spring 4 and suitable connectingmeans in contact with the lower ends of these electrodes, so as toconnect the same together. When current is supplied from thesupply-mains 5 6, it flows from the mains through leads 7 and 8 andthrough the starting-electrode 3, which forms a bridge between the endsof the electrodes 1 and 2. As soon as this current'fiows it energizes asolenoid 8 in series with one of the leads, as indicated, which solenoidthen operates upon a core 10, carrying the starting-electrode 3, andwithdraws this electrode from contact with the main electrodes 1 and 2.The are then starts between these latter electrodes and is controlledin'length and position by means of a magnetic field due to a coil orcoils 11, (represented in side elevation in Fig. 1 and in a plan view,partly in section, in Fig. 2.)

The current in the controlling coil or coils 11 is due to thedifferential effect of a main current in the arc and of a currentflowing in shunt to the arc. To secure this differential current, I makeuse of a transformer, represented with a single secondary coil 12 andtwo primary coils 13 and 14, all mounted on the same core 15. Theprimary coil 13 carries the main current of the lamp, While the coil 14is connected in shunt to the main electrodes 1 and 2, between which thearc is formed, and includes a series resistance 16 for adjusting andregulating the strength of this current. The connections are made sothat the shunt-coil and the series coil act in opposition to each other,thereby causing the current in the secondary coil 12 to represent thedifferential effect of the primary coils. As the arc starts it is boweddown from the ends of the electrodes by the magnetic field due to thecontrolling coil or coils 11, and this lengthening or bowing down of thearc continues until the increasing drop of potential across the are sofar counterbalances the effect of the main current of the lamp as tocause the current in the secondary 12, supplying the regulating coil orcoils 11, to reach a steady condition.

While Fig. 1 represents the lamp largely in diagram, Fig. 3 sets forththe same as it may be constructed in practice, and consists, asindicated, of a base-plate 17, carrying the regulating-transformer 18above, while suspended therefrom is the are producing and controllingmechanism, (represented at 19.)

In Fig. 4, which represents in diagram an arrangement made in accordancewith my invention for utilizing three-phase current, the threeelectrodes are represented at 20. While for clearness they are hererepresented side by side, it should be stated that in practice they arearranged triangularly, as indicated in Fig. 5, which shows a portion ofthe lamp in plan View and partly in cross-section.

The regulating-transformer for the lamp is indicated at 21 and comprisesa three-legged core, having mounted thereon series coils 22, in serieswith the supply-mains 23, shuntcoils 24, in shunt to the pairs ofelectrodes 20,

and secondary coils 25, mounted within inductive influence of the seriesand shunt coils.

These secondary coils supply, respectively, three con trolling-coils,(represented, perhaps, best at 26, 27, and 28 in Fig. 5,) the functionof these coils being substantially the same as the coils 11 in Fig. 2.Fig. 6 is a representation of a practical embodiment of the lamp shownin diagram in Fig. 4.

To start the lamp, a starting-electrode 29 is employed, this electrodewhen no current is passing in the lamp being maintained by a spring 30or other device in contact with the lower ends of the three electrodes20. When current is turned onto the lamp, the solenoid 31, in serieswith one of the mains 23, acts upon a magnetic core 32, which carriesthe starting-electrode 29, and withdraws the latter from contact withthe ends of the electrodes 20, thereby starting the are between theseveral pairs of electrodes. This arc, or the component portions of thearc, is controlled by the differential effect of the current in serieswith the lamp and the current in the several shuntcircuits about thearcs in a manner already described in connection with Fig. 1.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The combination of stationary electrodes, means forstarting an arebetween said electrodes, a coil for controlling said are, and means forsupplying said coil with a current due to the differential action of twocurrents,

I one flowing in shunt to the arc and the other in series therewith.

2. The combination of electrodes, means for starting an are between saidelectrodes, a coil for controlling said arc, and means for supplyingsaid coil with a current representing the difierential action of acurrent in series with the arc and a current in shunt to the arc.

3. The combination of electrodes arranged side by side, means forstarting an are between ends of said electrodes, a coil for controllingsaid arc, and means for causing current in said coil to decrease whenthe arc lengthens and increase when the are shortens.

4. The combination of electrodes placed out of line with each other,means for establishing an are between ends of said electrodes, a coilfor controlling said are, and means for causing current to flow in saidcoil of such value and direction as to represent a differential actionof the main current of the lamp and a voltage across the arc.

In witness whereof I have hereunto set my hand this 9th day of April,1902.

ELIHU THOMSON.

Witnesses DUGALD MoK. McKILLoP, ROBERT SHAUD.

